Colin Adlard – serving a life sentence for killing his wife of 30 years while she slept – is fed-up that lights are glaring “night and day”.

The 61-year-old murderer, who snapped after an argument with wife Wendy over mashed potato, is angry because he has been lectured about turning his electrical equipment off while wardens at Woodhill jail, Bucks, don’t have to.

In a letter to prisoner mag Inside Time the killer whined: “The Education Department spent a full week making us aware of how much damage we do by leaving electrical appliances, lights, etc on when it is not necessary.

“Meanwhile, the officers in the same prison leave all the lights on all night and day! The prisoners are requested to switch off cell lights and TV when leaving our cells but are forced to lay awake most of the night under the full glare of kilowatts of wasted light on the landings and in the grounds.”

He added: “No wonder prison budgets are straining, maybe if the staff were to stop wasting electricity we might be able to get somewhere with environmental issues and save a few quid at the same time.

“I swear, you couldn’t make it up!”

Adlard was jailed for a minimum of 16 years after striking his 59-year-old wife with a lump hammer while she was sleeping.

During his trial the court heard he saw red mist after becoming tired of his wife “shouting at him and nagging him over a long period of time”.

The former geophysicist pleaded guilty to murder and was jailed at Northampton Crown Court in September.